Internal-combustion engine



Dec. E8, 1923 S. l. PRESCOTT INTERNAL COMBUSTION ENGINE Filed Dec. 23 1920 il lillll'l'l Ilill Patented Dec. (l8, i923.

SYDNEY I. PRESCOTT, OF NEW YORK, N. Y.

INTERNAL-COMBUSTION ENGINE.

Application filed December 23, 1920. Serial No. 432,653.

To all whom it may concern:

Be it known that I, SYDNEY I. Pnnsoo'r'r, a citizen of the United States, residing at New York, county of New York, and State of New York, have invented a new and useful Improvement in Internal-Combustion Engines, of which the following is a specification.

This invention relates to improvements in internal combustion engines, particularly those of the rotary valve type.

The cylinders and valve housings of such engines are customarily constructed of cast iron which has a fixed coefficient of expansion; A-rotary valve must be a close fit-in its housing in order to insure proper suction and gas compression, or the engine cannot develop thepowcr for which it is designed; and it must not bind in its housing for that will destroy its utility. If a rotary valve is constructed of cast iron, and is a close in its housing when cold, it will insure proper suction and gas compression as the engine is started, but will invariably bind in its housing when -it is expanded, by hot exhaust gas contacting with it, to a greater extent than the housing is expanded. Numerous attempts have beenmade to overcome this difficulty by the use of some sort of cooling system for the valve, but such de-.

signs import new complications and difficulties of their own and have not proven efiicient for the designed purpose, mainly because it was found impossible by their use to maintain equal valve and housing temperatures since the valve and its housing are subjected to widely different degrees of heat. And if the valve is a loose fit in its housing when cold, so that when hot it will not bind therein, it is invariably inefficient for the essential suction and compression purposes, and therefore uneconomical and unsatisfactory. When a rotary valve was constructed of other metal, as some have been, the effect was worse. It has been discovered that the heretofore existing lack of control of the differential expansion of a rotary valve and its housing when subjected to the widely differing degrees of heat encountered in practical operation of internal combustion engines, is the underlying cause of the commercial failure of rotary valve engines heretofore built. And it has further been discovered that the difficulty can be overcome by constructing a rotary valve of an I alloy having a compensating coefficient of expansion determined in accordance with the working or actual expansion of the valve housing; or, in other words, by a rotary valve constructed of an alloy the composition of which depends upon the differential rates of expansion of a housing and its valve under Working or actual temperatures, the latter being determined by the former and sojustified with respect thereto .as to insure the maintainance of a close working fit of the valve in its housing throughout the range of working temperatures to which the parts are subjected. The production of such a compensated rotary valve is one of the ob jects of the invention.

Another difficulty heretofore encountered was the lack of efficient lubrication. The variations in the clearance of the valve in its housing, dueto their unequal expansion, operated against the proper retention of a film of oil between their surfaces, and the high heat of the exhaust gas contacting with and heating the valve operated to burn the oil unevenly, often before it could perform its lubricating function. It has been discovered that with a compensated rotary valve maintaining a practically constant working fit with its housing, this difficulty can be overcome by incorporating with the valve and housing organization an adequate self-contained lubricating means of the graphite bush type which successfully resists the heat and lubricates without interfering with the differential expansion of the parts. The production of such an organization is another object of the invention.

Furthermore, it is Well known that internal combustion engines of the two-stroke cycle type and engines of the four-stroke cycle type each have advantages and disadvantages peculiar to type, the former excelling in simplicity and the latter in efficiency. It has been discovered that in an organization including a compensated rotary valve efficiently lubricated there can be incorporated a closed cylinder having a piston working therein and dividing the cylinder into an induction chamber and a combustion chamber, with a suitable bypass connecting the chambers, and suitable port connections with a valve housing and intake and exhuast devices or manifolds, whereby the efficiency of a four-stroke cycle engine can be attained with the simplicity of an engine of the twostroke cycle type. The production of such an organization is still another object of the invention.

With these and other objects not specifically mentioned in view, the invention consists in certain combinations and constructions which will be hereinafter fully described and then Specifically pointed out is provided a communicating cylinder and valve housing, or a series of cylinders and a valve housing common to all cylinders, and a rotary valve Working in said housing and constructed of an alloy having a compensating coefiicient of expansion determined in accordance with the working expansion of the housing, whereby a'highly eflicient working fit of the parts is maintained at all working temperatures. In the best constructions, there is also provided se1fcontained lubricating means for the" valve and housing, and a closed cylinder, or series of closed cylinders, having a piston, or pistons, working therein and dividing the cylinder, or-each of the cylinders, into an induction chamber and a combustion chamher, the rotary valve controlling influxion and e'liluxion of gas to and from the cylinder chambers. Y

Theparticular structure selected to illustrate the invention is but one of many possible-concrete embodiments of the. same, and thevarious parts may be Widely varied in constructionwithin the invention as defined in the claims. The invention, therefore, is not to be restricted to the precise details of the structure shown' and described.

Although the invention is in part applicable to engines of the four-stroke cycle type, the. particular structure selected to illustrate it is a multi-cylinder engine ofthe twostroke cycle type the cylinders of which are duplicates in all essential particulars. In the drawing, the cylinder shown is marked 1, and is'provided with a water jacket 2 common to all cylinders and of a well known type; The cylinder is closed at its top by means of a water-jacketed and gasketed head 8 extending across all cylinders and bolted to the cylinder casting in the usual manner. At its bottom, each cylinder of the engine is provided with aflanged and. gaskete'd head 4 having a. stuffing box 5 of well known construction.

This lower head 4 serves also to locate the bore of its cylinder accurately in alignment with the bore of a 'crosshead chamber 6 rising from the crankcase of the engine, not shown. A circular crosshead 7 works in this chamber and carries a wrist pin 8 on which'is mounted one end of a connecting rod 9 and the forked end '10 of a piston rod 11. The: piston rod worksthrough the stufling box 5, and itsupper end is firmly secured to a piston 12 by. means ofan integral tapered section 13 and threaded secthe duct 17, it being understood that the duct 17 has no other outlet. Oil forced up through the duct 17 worksiits waythrough the hole 19 into the channel 20, and thence through the piston ducts 18 to and around the ring seat, behind the rings. being a close fit,just sufiicient oil for proper lubrication works between them to thesurface of the cylinder. Theoil: in thepiston ducts is not harmed by the heat of the piston because the piston is cooled-by fresh: gas which is constantly in the-cylinder :below the piston, and which prevents the piston from becoming as hofias in otherengines.

The source of oil supply is a partof the general oiling system of the. engine. In this system, oil is forced up through a pipe 21 from the crank shaft, not's'hown, to the wrist pin 8, the pipe being carried by the connecting rod in the usual'manner. In the present engine, this oil pipe is used, not only to conduct oil-to the wrist pin,-but beyond to the piston. lVith this end in view, the pipe is arranged'to discharge its oil into a groove 22 cut'in the wrist pin, and from this groove'a part ofthe oil works in between the pin and connecting'rod head to lubricate the same, while the surplus passes through a hole 23 in the connecting rod head into the duct 17 before referredto. By means of this structure, the piston is always eiliciently lubricated. The cross head 7 is lubricated in the manner. customary in trunk piston engines. 1

It will he noted that the piston 12 divides the cylinder into two chambers, the lower being an induction chamber 24 25aand the upper being a combustion cham'ber 26. The induction chamber lies partly within the "1 '1 he rings cylinder proper and partly outside of the same, the outer part being marked and in open communication with the inner part 24 by means of a series of ports 27 cut through the walls of the cylinders. The outer part of the induction chamber and the ports just described form a bypass around the piston when the latter is in its lowermost position. a

In whatever type of engine the invention is embodied, the cylinder will be in communication with a valve housing. In the two-stroke cycle engine illustrated, the cylinder block is of cast iron and in the same casting is formed a valve housing 28 located at one side of the cylinders and ex tending along the block within the water jacket 2. This valve housing has port con nection with the induction chamber 2 l25 by means of an intake port 29, and with the combustion chamber 26 by means of an exhaust port 30. The valve housing is also provided with an intake port 31 connecting it with an intake device or manifold 32, and with an exhaust port 33 con necting it with an exhaust device or mani fold Bel. It will of course be understood that when the invention is embodied in a single cylinder engine, there will be intake and exhaust pipes or devices, but no manifold. By an inspection of the drawing, it will be readily seen that the port connections between the cylinder and devices are crossed through the valve housing. The particular purpose of this arrangement will be hereinafter pointed out.

For the purpose of lubricating a rotary valve operating within the valve housing 28, the latter is lined with a bush 35 constructed of cast iron and provided with a multitude of heat-resisting graphite plugs 36. The bush is further provided with ports registering with the ports 29, 30, 31 and 33, and is held firmly against rotation in the housing.

The cylinder, valve housing, and bush, being constructed of the same metal, have the same coefficient of expansion, and since the water cooling system is designed to maintain the temperature of the castings at about 170 F, the working or actual expansion, or enlargementby heat, of the housing and bush is definite in extent.

Working in the valve housing 28, and lubricated by the bush 35, is a rotary valve 37 driven by suitable mechanism, not shown, from the crank shaft of the engine, and at half engine speed. This valve has through ports 38, one for each cylinder, and it rotates in the direction of the arrow circled about its axis. The hot exhaust gas passes through it and its working temperature is therefore considerably higher than the temperature of the valve housing and bush in which it works. To compensate for the differential working temperatures, and thus provide for a very close working fit of the valve and bush throughout the range of working temperatures between a cold and a. hot engine, the valve is constructed of an alloy having a compensating coefficient of expansion determined in accordance. with the working expansion of the valve housing and bush. in the engine illustrated, the valve housing bush is 2.500 in diameter, and the diameter of the compensated valve is 2.499, when cold. But when the valve housing and bush are expanded by heat to their working temperatures, the diameter of the bush is increased to 2.5022. To have the same clearance in the bush as when cold, the valve must be 2.5012 in diameter when at its working temperature, which, it will be remembered, is higher than that of the bush and housing. To attain this result, the valve, in the engine illustrated, is made of an alloy composed of approximately of iron and 30% of nickle. of expansion of this particular alloy is lower than that of cast iron; or, in other words, .its rate of expansion is slower. But in view of the higher temperature of the valve, its slower rate of expansion just compensates for the lower temperature but faster rate of expansion of the valve housing and bush, working temperatures. It may be here remarked that although the designed difference in diameter of the valve and bush is .001, which of course provides a clearance all around of .0005, this is not the actual clearance, because the surface of the valve when new quickly becomes covered with a film of graphite which reduces this clearance, lubricates and makes the valve gas tight, and is indestructible. By this construction, an extremely close working fit is made and maintained throughout the range of temperatures encountered in the practical operation of the engine.

When, however, an engine is designed to have a valve of a different diameter, the differential working expansions of the valve and its housing will be greater or less as the case may be, and in that event a slightly different alloy will be necessary, because the coefficient of expansion of this kind of alloy changes very rapidly when its component parts vary from the given proportion, and the alloy must always be determined in ac cordance with the working or actual expansion of the valve housing, and the pro portions of the metals in the alloy must be determined in accordance with an inherent coefficient of expansion which will compen sate for the changed expansion conditions existing in the new valve housing.

With the parts in the position shown in the drawing, the piston is in its uppermost position and the valve is controlling infiuxion of gas to the induction chamber The coefficient 24,-25, at this time by its own momentum, the valve being nearly closed. pressed in the combustion chamber is ignited and the piston is about to begin its downward movement on its power stroke. At 10 degrees of crank rotation, the valve closes the intake, and influxion ceases. At 130 degrees, the valve opens a passage from the port to the port 33 by way of its through port 38, and controls eftluxion of gas from the combustion chamber 26. During the downward movement of the piston under power, the fresh gas confined within the induction chamber is under initial compression, the greater part of it being forced out through the ports 2'7 into the outer part or the chamber, marked 25. The capacity of the induction chamber is such that the initial compression of the fresh gas therein is lower than its ultimate compression in the combustion chamber but greater than is customary in two-stroke cycle engines. This is to insure at the proper time a transfer of the from the induction chanr ber to the combustion chamber at high speed, so that the engine may run at high speed. When the piston reaches a position corresponding to 152 degrees oi crank rotation, it begins to uncover the ports 27, and the fresh gas confined in the induction cham-- her under low initial compression then rushes at high speed through the ports 27 into the combustion chamber from which the expended gas is rushing out, of its own momentum, having practically lost its pressure. The incoming fresh gas blows the remaining expended gas out and builds up behind it until the piston closes the bypass at 208 degrees. Just beyond this point, the valve closes the exhaust and immediately opens the intake, so that its through port, just swept by the hot exhaust gas, is immediately swept by the incoming cool gas, and the valve is thereby prevented from be coming excessively hot. This result is eilected by the crossed port connection of the valve housing with the chambers and manifolds before referred to. As the piston moves upward, the charge of gas confined within the combustion chamber receives its high ultimate compression for ignition, and fresh gas is cr 'wn into the induction chamher. And just before the piston again reaches its uppermost position, the compressed charge is ignited and the engine cycle of operation is repeated.

By the operation of this construction, the influxion and cffluxion of gas is as positive as in an engine of the tour-stroke cycle type, and although the quantity of gas used is slightly less than it would be in an engine of that type having the same bore and stroke, because the piston rod reduces the capacity of the induction chamber, its flexibility is as great as that of a far more costly Thegas com four-stroke cycle engine havin double its number of cylinders, and its e ciency is as great, while its simplicityis comparable with that of'a two-stroke cycle engine of ordinary design. i

What is, claimed is:

1. In an internal combustion engine,"the combination with a closed cylinder, of a piston working'therein and dividing said cylinder into an, induction chamber and a combustion chamber, a valve housing having port connection with said chambers, and a compensated rotary valve working in said housing and controlling influxion'to said-induction chamber and eiiluxion from said combustion chamber.

2. in an internal combustion engine, the

'combinat-ion with a closed cylinder, of a piston working therein and dividing said cylinder into an induction chamber and a combustion chan'iber, intake and exhaust devices, a valve housing having crossed port connection with said chambers and devices, and a compensated rotary valve working in 5 id housing and having a through port swc pt by eiiiuxion of hot gas and immediately afterward by iniluxion of cool gas.

25. in an internal combustion engine, the combination with a closed cylinder, of a piston working therein and dividing said c linder into an induction chamber and a combustion chamber, a valve housing hav ing port connection with said chambers, a compensated rotary valve working in said housing and controlling influxion to said induction chamber and effluxion from said combustion chamber, and self-contained lubricating means for said valve and housing.

4. In an internal combustion engine, the combination with a closed cylinder, of a piston working therein and dividing said cylinder into an induction chamber and a combustion chamber, avalve housing having port connection with said chambers, a lubricating bush lining said housing, and a compensated rotary valve working in said bush and controlling infiuxion to said induction chamber and efiiuxion from said combustion chamber.

5. in an internal combustion engine, the combination with a closed cylinder, of a piston working therein and dividing said cylinder into an induction chamber and a combustion chamber, a valve housing having port connection with said chambers, a

cylinder into an induction chamber and a combustion chamber, a valve housing having port connection With said chambers, and a rotary valve working in said housing and controlling influxion to said induction chamber and efiiuxion from said combustion chamber said valve being constructed of. an alloy having a compensated coefficient of expansion determined in accordance with the working expansion of said housing.

7. In an internal combustion engine, the combination with a closed cylinder constructed of cast iron, of a piston working therein and dividing said cylinder into an induction chamber and a combustion chamber, a valve housing having port connection with said chambers, and a rotary valve working in said housing and controlling influxion to said induction chamber and eiiluxion from said combustion chamber, said valve being constructed of an alloy com posed of approximately 70% of iron and 30% of nickel.

8. In an internal combustion engine, the combination with a closed cylinder constructed of cast iron, of a piston working therein and dividing said cylinder into an induction chamber and a combustion chamber, intake and exhaust devices, a valve housing having crossed port connection with said. chambers and devices, a lubricat ing bush lining said housing, and a rotary valve working in said bush and controlling influxion to said induction chamber and efiiuxion from said combustion chamber, said valve being constructed of an alloy of aproximately 70% of iron and 30% of nickel and having a through port swept by eifiuxion of hot gas and immediately afterward by influxion of cool gas.

9. In an internal combustion engine, the

combination with a closed cylinder, of a piston working therein and dividing said cylinder, into an induction chamber and a combustion chamber, a piston rod secured to said piston, a valve housing having port connection with said chambers, and a compensated rotary valve working in said hous ing and controlling iniiuXion to said induction chamber and efliuxion from said combustion chamber, said piston rod and piston having communicating ducts adapted to conduct lubricant to said piston.

10. In an internal combustion engine, the combination with a closed cylinder, of a piston provided with a ring seat and working in. and dividing said cylinder into an induction chamber and a combustion chamber, a piston rod secured to said piston, a valve housing having port connection with said chambers, and a compensated rotary valve working in said housing and controlling infiuxion to said induction chamber and eiiluxion from said combustion chamber,

said piston rod having a single oil duct and said piston having a plurality of oil ducts connecting the piston rod duct with said ring seat.

11. In an internal combustion engine, the combination with a closed cylinder, of a piston working therein and dividing said cylinder into an induction chamber and a combustion chamber, a piston rod secured to said piston, and compensated means controlling influXion to said induction chamber and efiiuxion from said combustion chamber, said piston rod and piston having communicating ducts adapted to conduct lubricant to said piston.

In testimony whereof, I have signed my name to this specification.

SYDNEY I. PRESCOTT. 

